Respiratory Syncytial Virus Infection

name: Respiratory Syncytial Virus Infection
creation_date: "2026-06-25T12:00:00Z"
description: >
  Respiratory syncytial virus (RSV) infection is an acute respiratory infection
  caused by human respiratory syncytial virus (human orthopneumovirus; family
  Pneumoviridae), a negative-sense single-stranded RNA virus. RSV infects the
  ciliated respiratory epithelium; its fusion (F) glycoprotein mediates entry and
  cell-cell fusion producing characteristic multinucleated syncytia. RSV is a
  leading cause of bronchiolitis and pneumonia in infants and one of the leading
  infectious causes of infant death worldwide, and is an increasingly recognized
  cause of serious lower respiratory illness and cardiopulmonary decompensation
  in older and high-risk adults. Severe early-life RSV is mechanistically linked
  to later wheezing and asthma, and RSV hospitalization in older adults is
  associated with subsequent cardiovascular events including heart failure.
category: Infectious Disease
parents:
- Viral Respiratory Infection
synonyms:
- RSV infection
- Human respiratory syncytial virus infection
- Human orthopneumovirus infection
disease_term:
  preferred_term: respiratory syncytial virus infection
  term:
    id: MONDO:0001577
    label: respiratory syncytial virus infectious disease
infectious_agent:
- name: Human respiratory syncytial virus
  infectious_agent_term:
    preferred_term: Human respiratory syncytial virus
    term:
      id: NCBITaxon:11250
      label: human respiratory syncytial virus
  description: >
    A negative-sense, single-stranded RNA virus (Pneumoviridae). The attachment
    (G) and fusion (F) surface glycoproteins mediate binding and membrane
    fusion; F is the principal target of monoclonal-antibody prophylaxis and
    current adult/maternal vaccines.
pathophysiology:
- name: Respiratory Epithelial Infection and Airway Inflammation
  description: >
    RSV infects ciliated airway epithelial cells, and its fusion protein drives
    cell-cell fusion producing multinucleated syncytia. Epithelial injury,
    sloughing of necrotic epithelium, mucus hypersecretion, and an inflammatory
    cellular infiltrate obstruct the small airways (bronchiolitis), causing air
    trapping and ventilation-perfusion mismatch. The host inflammatory and
    immune response contributes substantially to disease severity. In older and
    high-risk adults the same infection can precipitate cardiopulmonary
    decompensation.
  cell_types:
  - preferred_term: respiratory epithelial cell
    term:
      id: CL:0002632
      label: epithelial cell of lower respiratory tract
  - preferred_term: ciliated airway epithelial cell
    term:
      id: CL:0002145
      label: multiciliated columnar cell of tracheobronchial tree
  biological_processes:
  - preferred_term: viral genome replication
    term:
      id: GO:0019079
      label: viral genome replication
  - preferred_term: defense response to virus
    term:
      id: GO:0051607
      label: defense response to virus
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
    modifier: INCREASED
  locations:
  - preferred_term: bronchiole
    term:
      id: UBERON:0002186
      label: bronchiole
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:27903593
    reference_title: "Respiratory Syncytial Virus: Infection, Detection, and New Options for Prevention and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Respiratory syncytial virus (RSV) infection is a significant cause of hospitalization of children in North America and one of the leading causes of death of infants less than 1 year of age worldwide, second only to malaria."
    explanation: Establishes the major pediatric burden of RSV lower respiratory infection.
  - reference: PMID:27903593
    reference_title: "Respiratory Syncytial Virus: Infection, Detection, and New Options for Prevention and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Compounding the burden of acute RSV infections is the exacerbation of preexisting chronic airway diseases and the chronic sequelae of RSV infection."
    explanation: Supports that RSV exacerbates chronic airway disease and has chronic sequelae beyond the acute infection.
  - reference: PMID:15858184
    reference_title: "Respiratory syncytial virus infection in elderly and high-risk adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Respiratory syncytial virus (RSV) is an increasingly recognized cause of illness in adults."
    explanation: Supports RSV as an important respiratory pathogen in adults, not only children.
phenotypes:
- category: Respiratory
  name: Cough
  description: Common feature of upper and lower RSV respiratory illness.
  phenotype_term:
    preferred_term: Cough
    term:
      id: HP:0012735
      label: Cough
- category: Respiratory
  name: Wheezing
  description: Small-airway obstruction in RSV bronchiolitis.
  phenotype_term:
    preferred_term: Wheezing
    term:
      id: HP:0030828
      label: Wheezing
- category: Respiratory
  name: Dyspnea
  description: Breathlessness from bronchiolitis/pneumonia.
  phenotype_term:
    preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
- category: Respiratory
  name: Tachypnea
  description: Rapid breathing, prominent in infant bronchiolitis.
  phenotype_term:
    preferred_term: Tachypnea
    term:
      id: HP:0002789
      label: Tachypnea
- category: Respiratory
  name: Hypoxemia
  description: Low blood oxygen from ventilation-perfusion mismatch.
  phenotype_term:
    preferred_term: Hypoxemia
    term:
      id: HP:0012418
      label: Hypoxemia
- category: Respiratory
  name: Apnea
  description: Can occur in young infants with severe RSV.
  phenotype_term:
    preferred_term: Apnea
    term:
      id: HP:0002104
      label: Apnea
- category: Constitutional
  name: Fever
  description: Common during acute infection.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
treatments:
- name: Supportive Care
  description: >
    Mainstay of management is supportive (oxygen, hydration, respiratory
    support); few specific therapeutics exist.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:27903593
    reference_title: "Respiratory Syncytial Virus: Infection, Detection, and New Options for Prevention and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite its global impact on human health, there are relatively few therapeutic options available to prevent or treat RSV infection."
    explanation: Supports that specific therapeutics are limited and management is largely supportive.
- name: Vaccination
  description: >
    RSV vaccines (and maternal immunization / monoclonal-antibody prophylaxis)
    are now used to prevent severe RSV, including in older adults in whom RSV
    drives serious cardiopulmonary outcomes.
  treatment_term:
    preferred_term: Vaccination
    term:
      id: NCIT:C15346
      label: Vaccination
  evidence:
  - reference: PMID:40696870
    reference_title: "Respiratory Syncytial Virus (RSV)-Related Hospitalization and Increased Rate of Cardiovascular Events in Older Adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "they underline the importance of vaccination in this population, regardless of pre-existing risk factors."
    explanation: Supports vaccination of older adults to prevent serious RSV-associated outcomes.
- name: Nirsevimab
  description: >-
    Nirsevimab is a long-acting recombinant monoclonal antibody against the RSV
    fusion (F) protein, given as a single injection for passive immunoprophylaxis
    of infants before the RSV season. By neutralizing the F protein it blocks
    viral entry/fusion, preventing medically attended RSV lower respiratory tract
    infection — a broad-spectrum-preventative (passive-immunity) approach.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: nirsevimab
      term:
        id: NCIT:C170224
        label: Nirsevimab
  target_mechanisms:
  - target: Respiratory Epithelial Infection and Airway Inflammation
    treatment_effect: INHIBITS
    description: >-
      Nirsevimab neutralizes the RSV fusion (F) protein that drives epithelial
      entry and syncytium formation, preventing productive airway-epithelial
      infection upstream of bronchiolitis.
    evidence:
    - reference: PMID:35235726
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        A single injection of nirsevimab administered before the RSV season
        protected healthy late-preterm and term infants from medically attended
        RSV-associated lower respiratory tract infection.
      explanation: >-
        MELODY randomized-trial evidence that nirsevimab prophylaxis prevents
        medically attended RSV lower respiratory tract infection. Evidence source
        is HUMAN_CLINICAL as this is a randomized controlled trial.
  evidence:
  - reference: PMID:35235726
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      monoclonal antibody to the RSV fusion protein that has an extended half-life.
    explanation: >-
      Identifies nirsevimab as a long-half-life monoclonal antibody targeting the
      RSV fusion protein. Evidence source is HUMAN_CLINICAL as this is a randomized
      controlled trial report.
notes: >
  Created as an endpoint entry to support directional comorbidity/trajectory
  modeling of RSV infection as an antecedent of cardiovascular events
  (heart failure) in older adults and of early-life wheezing/asthma.